if someone is in a table then?

I'm assuming that you want to check if a player is in the table called hosts and to check that it would be simple:

local hosts = {"imaginaryjeffery321"}
for i,v in pairs(hosts) do
	for i2,p in pairs(game.Players:GetPlayers()) do --This will loop through all the player's currently in the game
		if p.Name == v then --p.Name because the value in hosts is a string value and not a player object.
			--Whatever stuff you want, host priveleges presumably.
			break
		end
	end
end

However, if you want to check if a player is in that table when they join. That'll be like so:

local hosts = {"imaginaryjeffery321"}
game.Players.PlayerAdded:connect(function(ply) --This is called whenever a player is added.
	for i,v in pairs(hosts) do
		if ply.Name == v then --p.Name because the value in hosts is a string value and not a player object.
			--Host stuff
			break
		end
	end
end)

Hope this is what you were looking for.